Optical fibers typically are polymer coated to protect them against damage. During fiber manufacture and subsequent handling, it is necessary to maintain the interfacial bond between the (typically silica) fiber and the coating that contactingly surrounds the fiber. This coating is frequently referred to as the "primary" coating. A further coating that surrounds the primary coating is frequently referred to as the "secondary" coating.
The interfacial bond between the fiber and the primary coating desirably is strong to prevent bond failure during fiber manufacture and subsequent handling. Such failure can result in the formation of a "delaminated" area which can adversely affect the optical performance of the fiber. A delaminated area is characterized by an air gap at or near the interface of the fiber and the primary coating. The air gap typically alters the mechanical properties at the point of delamination, and may cause fiber transmission losses. Even if the optical performance is substantially not affected, the presence of delamination can result in negative customer perception and is therefore unacceptable. Thus, the fiber/primary coating bond desirably should be robust.
On the other hand, during fiber installation and many other operations it is necessary to easily and cleanly remove the coating from a portion of the fiber. For this reason it is necessary that the fiber/primary coating bond strength be not too great.
From the above discussion it is apparent that the strength of the fiber/primary coating bond is an important characteristic of an optical fiber. This strength can be expressed in terms of a delamination resistance. It will also be apparent that it would be highly desirable to have available a simple, reliable method of determining the delamination resistance. Such a method could be used during fiber manufacture as a quality control method, but could also be used during development of a new coating. This application discloses such a method, and apparatus that facilitates practice of the method.